1. Field of the Invention
The present invention relates to an organic thin film transistor array substrate, and more particularly to an organic thin film transistor array substrate in which the dielectric layer underlying the pixel electrode has an uneven structure.
2. Description of the Prior Art
In recent years, organic semiconducting material has drawn many researchers' attention and has proven to be one of the most popular candidates in fabrication of thin film transistors (TFTs) and various electronic and optoelectronic devices. Organic semiconducting material is easy to fabricate, increasing the chance of its future application in flexible displays.
An organic thin film transistor (OTFT) is a TFT that uses an organic layer to serve as the active layer and has been used to drive liquid crystal displays (LCDs). In recent years, in order to simplify the process and decrease production cost, some researchers have developed integration technology that fabricates the LCD and OTFT monolithically (i.e., on the same substrate).
For example, Kabushiki Kaisha Toshiba in U.S. Pat. No. 5,355,235 discloses an integrated device of LCD and bottom-gate OTFT, in which two organic layers are used in the OTFT structure.
Mitshubishi Denki Kabushiki Kaisha in U.S. Pat. No. 6,060,333 discloses a bottom-gate OTFT structure combined with a transmissive or reflective type LCD. For the reflective LCD, the reflector sheet is simply a mirror surface; therefore, the display effect (reflectivity and contrast) is inferior.
Hitachi, Ltd. in U.S. Pat. No. 6,300,988 B1 uses a bottom-gate OTFT combined with an LCD. A patterned insulating layer is used to make the overlying deposited organic semiconducting layer have a pattern, thus separating into a channel region and a non-channel region. Thus, current leakage and crosstalk between devices decreases.
For the above-mentioned reflective or transflective LCD driven by OTFT, the display effect requires improvement.